Expansion reamee



Jan. 27, 1931.

' L. o. BEARD EXPANSION REAMER Filed A ril 25. 1929 INVENTOR. Y W @[W BY A TTORNE Y.

Patented Jan. '27, 1931 LAWRENCE o. EARD, or LANCASTER, rnnnsxnvnnm l a I EXPANSION nEAMEa Application filed April 25,

My invention relates to expansion reamers and more particularly to that class of reamers adapted for truing the piston bores of internal combustion engine pistons.

The principal object of the invention is to provide an expansible pilot sleeve which will be automatically expanded when the cutting blades of the reamer are expended.

Another object of the invention is to in cate the pilots close to the opposite ends of the cutting blades, to stiffen the reamer and to prevent it from springing and chattermg.

Other and more specific objects and ad 7.5 vantages of the invention will be apparent as the specification is considered in connection with the accompanying drawing, in which:

Figure 1 is a side elevation of a reaming cutter embodying the invention, and shows in outline a piston to which the reamer is applied, the reamer being shown as it ap- PBZII-IS during the reaming of the first piston ho e;

Figure 2 is a view similar to Figure 1 showing the reamer as the second piston hole is being reamed;

Figure 3 is a longitudinal section view of the reamer with the expansible pilot removed, and showing the means for expanding the pilot.

Figure 4 is a section on line 44 of Figure 3. 4

Referring more particularly to the drawings wherein the same reference numerals indicate like parts in all the figures, 1 represents the reamer having the hollow-shank 2, the free end of which is squared as at 3 to facilitate attachment of a wrench or other operating tool. The outer open end of the bore 4:, of the shank 2, is internally threaded as at 5 for the purpose of threadedly receiving the reduced threaded portion 8 of an expander 8, the purpose ofwhich will be explained hereinafter.

Cutting blades 6 are integrally formed on the intermediate portion of the shank and in order to impart flexibility to the blades, that is permit expansion and contraction thereof, by means of the expander member 'on which the cutting blades are formed and 1929; Serial No. 358,067. g

8,'elongated slots v7 are cut or otherwise formed therein. 1 These'slots extend through and -forsubstantially the same distance'beyond each end of that portionof the shank are inclined at a slight angle to the axis of the: reamer. The cutting blades aresimilarly inclined but to a slightly greater degree than the slots;

- Mounted on the outer open end of the shank 2 is'a springv steel pilot sleeve 11 which is provided with longitudinally, extending slots 12 at its inner .end. The diameter ofthe bore 13'of the pilot sleeve is the same or slightly less than thatofthe hollow shank 2, so that sleeve :will fit snugly there'over. The purpose ofthe slots 12 is to permit the pilot sleeve to expandand contract.

V lWhenvthe cutting face of the blades 6 of the reamer 1 Wear down, or when it is desired to increase theircutti'ng capacity, expander 8 is screwed home in the bore 4 until the beveled end 9 of the member 8 engages the, shoulder 10,-thus causing the flexible or expansible portions or areas adjacent the blades to give. I

As the bladed portion of the reamer shank expands, the slotted portion of the pilot sleeve .11 will also be correspondingly expanded and conversely when the. expander member 8 is unscrewed to reduce the cutting range of the cutters, the pilot sleeve will automatically contract, the sleeve being sufficiently resilient and flexible for this'purpose. The outer circumference of the pilot sleeve is preferably about one one-thousandth of an inch smaller than the circumference of the cutting lades, fora purpose presently explained.

the operation of reaming the bore 12. the

reamer is steadied and guided in bore 13 by the pilot sleeve 11 which engages therein. 7

As the outer circumference of the pilot sleeve is substantially the same as that of the cutting blades, being only one one-thousandth of an inch smaller, the sleeve will slide freely through the bore 13 but at the same time Will maintain the forward end of the reamer in substantially the same horizontal plane as the cutter port-ion thereof. It also follows that Where it is found necessary to expand the cutting range of the cutters 6, by expanding the reamer, that the pilot sleeve Will be correspondingly and automatically expanded, thus maintaining the circumference of sleeve substantially the same as the circumference of-the cutters.

Continued turning of the reamer by means of a tool applied to the squared end 3causes the cutter blades 6 to progressively enlarge the bore 12 as the reamer is fed steadily for- Ward, itbeing understood that the piston 14 will be clamped in a suitable vise not shown, thus leaving the operators hands free to operate the device.

When the bore 12 has been reamed, and the blades 6 emerge therefrom, the reamer is pushed endwise through the bores 12 and 13 until the blades engage the bore 13'. A tapered centering sleeve 15, Which fits the reamer snugly. and is of substantially the same circumference as the pilot sleeve, is then placed over the squared end of the reamer shank and inserted in the bore 12', which has just been reamed. The reaming is then continued, it being noted that the expansible pilot sleeve and the small tapered centering sleeve support and steady the reamer during this operation. It Will also be noted that the pilot sleeve'and the small centering sleeve engage and support the cutter portion of the reamer shank, at points closely adjacent the cutters, thus preventing chattering.

Having thus described my invention, What I claim is:

A reamer for truing opposing piston pin holes comprising a hollow shank formed With an expansible portion, said expansible portion having exterior cutting blades integrally formed thereon intermediate of its length, said expansible portion being formed interiorly with a shoulder intermediate the ends of said cutting blades, a slotted expansible pilot sleeve fitting snugly upon the shank adjacent said cutting blades and an expanding member for simultaneously expanding and contracting the expansible portion of the reamer and the slotted portion of the pilot sleeve, said member being threadedly received Within said hollow shank and having a tapered portion for engaging said shoulder for effecting uniform expansion of said cutting blades.

In testimony whereof I affix my signature.

LAlVRENCE O. BEARD. 

